No matter what type of food you offer, your goal is to provide the number of calories necessary to maintain a healthy body weight. So, let’s say you are switching your 60 pound, neutered dog from a dry to a canned food with the primary purpose of increasing his protein intake. He is currently taking in 1400 calories a day and he is still going to need 1400 calories worth of his new food to maintain his weight despite the fact that the volume and weight of his meals are going to change dramatically.

Dr. Justin Shmalberg, Diplomate ACVM, describes how we can compare foods on a per-calorie basis:

Step 1 – Add 1.5% to the protein percentage and 1% to the fat percentage from the pet food label

Step 2 – Divide kcal/kg by 10,000 (also on the label)

Step 3 – Divide estimated protein % and fat % by number obtained in Step 2 to get the result in grams/1000 kcal

Here’s an example of how it works. Let’s compare the protein percentages of Dry Dog Food A and Canned Dog Food B.

Dry Dog Food A

3589 kcal/kg

Crude Protein, minimum

24.0%

Crude Fat, minimum

12.0%

Crude Fiber, maximum

4.0%

Moisture, maximum

10.0%

Canned Dog Food B

960 kcal/kg

Crude Protein, minimum

8.00%

Crude Fat, minimum

3.00%

Crude Fiber, maximum

1.50%

Moisture, maximum

84.00%

Using the steps outlined above…

Dry Dog Food A

Step 1 – 24% + 1.5% = 25.5%

Step 2 – 3589 / 10,000 = 0.3589

Step 3 – 25.5 / 0.3589 = 71 g protein/1000 kcal

Canned Dog Food B

Step 1 – 8% + 1.5% = 9.5% protein

Step 2 – 950/10,000=0.095

Step 3 – 9.5 / .095 = 100 g protein/1000 kcal

Therefore, the canned food in this comparison is significantly higher in protein than is the dry.

You’ll still have to calculate the estimated carbohydrate percentage of any pet foods you are interested in since this number does not have to be reported on the label. See last week’s post to learn how to do this. Once you have that information in hand, you can use steps 2 and 3 to compare the carbohydrate percentages of different foods.